The present invention relates to a device on portable machine tools.
More particularly, it relates to a device on portable machine tools, in particular portable drilling or percussive appliances, which is suitable for transmitting a rotary and/or a percussive movement to a tool having rotary driving grooves open toward an end of the shank and a location hole with inwardly projecting rotary driving elements engaging in the grooves of the tools.
Devices of the above-mentioned general type are known in the art. One such device is that disclosed for example in WO DE88/00260. However, it is only possible to insert into these tools with open grooves distributed non-uniformly over the circumference. The rotary driving elements of the known device are arranged asymmetrically and thus prevent universal use. In particular, the tools suitable for this device are not compatible with other tool holders such as drill chucks. On the one hand, there is the risk that some of the chuck jaws will engage in the existing grooves, leading to eccentric gripping, and, on the other hand, there is no axial mobility of the tool in drill chucks. However, a limited axial mobility is very advantageous in the case of impact drilling tools since then, when striking, only the tool itself and not, in addition, parts of the chuck have to be moved.
Tools are inserted into the device. Another tool is known from DE-A-34 29 419. This tool can be gripped in drill chucks with three jaws and inserted into tool holders of certain hammer drills. The tools have a closed groove for locking in the hammer drills. In percussive operation, this groove for the rotary driving and locking elements is subjected to severe loading. Since it is only partially closed, there is the risk, in the case of worn-out shanks, that the tool will be released unintentionally. Furthermore, the known tools are not suitable for hammer drills with tool holders which have inwardly facing rotary driving strips.
It is disadvantageous for use in machines with drill chucks that the design of the grooves in the shank PG,3 of these tools permits only fixed gripping without axial mobility of the tool. However, a limited axial mobility is very advantageous in the case of impact drilling tools since then, when striking, only the tool itself and not, in addition, parts of the chuck have to be moved. There is thus no axial securing of the tool when it is used in drill chucks. The known shank design is thus not suitable for universal application and as a standard shank shape for various types of portable drilling or percussive appliances and all applications.